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USA Medallion

I've been working on a USA medallion recently, and wanted to add a flickering effect. Something to make the lights twinkle randomly. That's not too hard on a real PC, where resources are cheap. But the ATTiny 44 I'm working on has only 128 bytes of ram. (That's 1/8th of a kilobyte, which is 1/1000th of a megabyte, which is itself 1/1000th of a gigabyte, which is what your computer has.)

Most of the RNG's around need 4 bytes or so for storage, and more for calculation. Mine doesn't! (It's also not very random, but you can't have everything for free.)

Here's the USA outline I'm making into copper. I used the GIMP to mask off parts for continuity.

Ain't plaintext great?

Final board with copper outlines.

For my trinket, I wanted to make the front side unmasked copper, since it's shiney and reflective and looks cool. KiCad supports converting graphics to component files, but only for the silkscreen (user text) and soldermask (the green stuff) layers. But, with the new plaintext components, it's trivial to get graphic copper. Here's how.

Start by opening Bitmap2Component. From the main KiCad window, it's the icon to the side here. That'll open the program shown below. You can follow the usual way of creating a component: click on Load Bitmap, adjust the threshold value to select which parts are in the component file, and so on. The Black&White tab shows the final outline. For copper, try to use a resolution above 300dpi (600 or 1200 is best); modern processes can create really, really small features, and you want to take advantage of that. When you're done, save it as a Pcbnew file (.kicad_mod). It doesn't much matter which layer you use, but I'll pretend you're using the Front Silk Screen layer.